EP2137359B2 - Façade insulating board for insulating exterior façades of buildings, heat insulating composite system having such façade insulation boards, and method for producing a façade insulating board - Google Patents

Description

The invention relates to a composite thermal insulation system according to the preamble of claim 1 and to the use of a facade insulation panel according to claim 15.

Such facade insulation panels are mostly used in thermal insulation composite systems in which they form an insulating layer arranged side by side on a facade. The facade insulation panels are typically glued to the building facade and fixed by means of plate dowel. These penetrate the façade insulation panels and, with their large dowel plates, secure the position of the facade insulation panels on the façade. On the outside of the facade insulation panels and the anchor plate, an external plaster is attached to a thermal insulation composite system, which usually has a flush with an embedded reinforcing layer and a finishing coat as the outer edge.

The facade insulation panels in such a thermal insulation composite system are exposed to loads due to their own weight, by hygrothermal effects and in particular by wind suction. The interaction of the adhesive mortar with the plate anchors causes the power dissipation and thus the stability of the thermal insulation composite system.

As a result of shrinkage of the plaster and hygrothermal effects, such as temperature and humidity fluctuations, constraining stresses occur in the plaster system and shifts of the outer skin in the facade edge areas or field edge areas in large, divided plaster surfaces. With the shifts in disk plane shear forces are connected, which are superimposed on the forces of dead loads. With regard to the usability of such a composite thermal insulation system is so far only significant, whether the constrained stresses can cause cracks, and in terms of stability is only ruled out that the hygrothermal shifts to shedding or shearing of the system in Fassadenrand- and Fassadeneckbereichen to lead.

In practice, it has been shown that the anchor plates of anchoring dowels can be visible in the cleaning surface over time. In cases where this optical defect is to be safely ruled out, one has gone over to operate an additional installation effort and sunk the plate dowel in the facade insulation panels, then cover them with a plug of mineral wool. This measure also reduces the unavoidable in a flat on a facade insulation board plate dowel thermal bridge.

The greatest mechanical load of the thermal insulation composite system is generally due to the wind suction forces. These lead perpendicular to the ground on the cross section of the thermal insulation composite system acting tensile forces in this and thus also in the facade insulation panels that are absorbed by the dowels and discharged into the ground. The adhesive mortar remains out of consideration here in the stability tests. In tear tests for experimental determination of the required number of anchors no adhesive mortar is used.

Such facade insulation elements or thermal insulation composite systems go by way of example from the EP 1 088 945 A2 , the EP 1 408 168 A1 and the DE 103 36 795 A1 out. The facade insulation panels used for this purpose are formed as a homogeneous, single-layered mineral wool body, in particular rock wool is used. Such facade insulation panels are now used regularly for insulation systems that comply with the heat conduction group 040, ie a design value of thermal conductivity λ = 0.040 W / mK according to DIN EN 13162.

An essential factor for the stability of such a thermal insulation composite system lies in the material properties of the facade insulation panels, from which the insulation layer is formed. These must have a sufficient tensile strength perpendicular to the plate plane (transverse tensile strength) to withstand the input described loads and in particular the wind suction loads, without causing a destruction of the fiber structure and thus a detachment of parts of the facade. The opposite is the demand for the lowest possible thermal conductivity of the insulating layer in order to achieve the best possible insulation effect of the system can. In today's usual gross density ranges of Fassadendämmplatten these two effects are in opposite directions, so that the improvement of one property is accompanied by a deterioration of the other.

Of considerable economic importance for a thermal insulation composite system is required for stability reasons number of plate dowels, since they are very expensive and especially their attachment to the facade is labor-intensive, creating an interest justified to keep their number as low as possible. This number is determined on the basis of a stability certificate, in particular the building height and the Wind suction loads. The wind suction loads are based on the requirements of DIN 1055 Part 4. The number of dowels required depends on the total force to be removed and the possible load transfer per individual dowel. Depending on the boundary conditions, the current dowel numbers are between 4 and 12 dowels / m ² for the thermal insulation composite systems of the heat transfer group WLG 035.

In order to avoid an increase in the number of dowels, a two-layer facade insulation board with a compacted covering layer on the plaster side and an insulating layer with a lower density on the facade side is conventionally used for an insulation system according to WLG 035. Such multi-layer insulation boards can be, for example, from one according to DE 37 01 592 A1 or. EP 0 277 500 A2 Assemble produced mineral wool web. This has a compressed cover layer, which consists of the same material as the lower layer and also has a laminar fiber orientation. In such a prefabricated facade insulation board can be due to the hard outer layer good power transfer from the anchor plate to the adjacent areas and thus achieve an advantageous fixation of the insulation board on the facade. However, it is not useful in this embodiment to make a recess to sink the plate dowel, since then eliminates the stabilizing effect of the hard cover at least in the area of the plate dowel due to the severed cover layer, and thus just no force is applied via the cover layer in the plate dowel.

From the house of the applicant of the present patent application, the product "Sillatherm" is also known, which also uses a two-layer facade insulation board to achieve the Wärmeleitgruppe 035. This insulation board has a lower layer of laminar mineral wool, which especially due to their fiber orientation unfolds a good insulation effect. On the outer plaster facing side of this, a cover layer with mineral wool in three-dimensional isotropic orientation of the fibers is arranged, which has significantly better strength properties than the lower layer with slightly poorer insulating properties. Such a mineral wool layer with three-dimensional isotropic fiber orientation can be, for example, by the method according to the DE 103 59 902 A1 achieve. In this case, a primary non-woven with a laminar fiber structure, so largely parallel to the large surfaces aligned fibers, digested, ie isolated with the formation of mineral wool flakes, which can be done for example by means of combing rollers or carding machines. Subsequently, the respectively obtained mineral wool flakes or individual fibers are re-combined to form a secondary nonwoven, whereby this results in a quasi-isotropic fiber orientation in all three dimensions directions. For further details, reference is made to the content of this document.

This approach has led to a product which can also be advantageously used in practice for the heat conduction group 035. However, to prove the required stability, it is necessary to use anchor plates with a diameter no smaller than 90 mm, or to use a large number of plate anchors with a smaller diameter. The latter variant is not practical or acceptable for cost reasons in terms of labor and time. In addition, the dowel plates in the product "Sillatherm WVP 1-035" can not be sunk in the facade insulation board.

The document DE 102 41 231 A1 discloses a thermal insulation composite system with the features of the preamble of claim 1. However In this prior art, a basket-shaped insert is used as a force-distributing element.

The invention is therefore based on the object, a thermal insulation composite system with an insulating layer of Fassadendämmplatten for the insulation of external facades of buildings in such a way that such Fassadendämmplatte with recessed plate dowels for systems with a design value of thermal conductivity λ <0.040 W / mK according to DIN EN 13162 can be used without an increased number of plate anchors over the prior art for their attachment to the facade is required.

This object is achieved by a thermal insulation composite system with the features of claim 1.

The invention provides an inhomogeneous binder distribution over the thickness of a facade insulation board. In particular, it was recognized in the invention that the combinatorial interaction of the advantageous in terms of thermal insulation laminar undercoat with the cover layer, which combines the advantage of a further good thermal insulation behavior with the other advantage of good inherent stability of the layer, as well as an integral in the Boundary layer between this cover layer and the laminar lower layer present situation with increased binder content can achieve a facade insulation board, which is characterized by a particularly reliable stability. Here plays in the installed state in a thermal insulation composite system, the interaction with the plate anchors an essential role, as the through the dowel plate on the facade insulation board applied holding force is transmitted through this inner layer with increased binder content in a particularly suitable manner to adjacent areas.

It is of further importance that the inventively chosen special design of a facade insulation board brings despite significant improvement of their inherent stability and strength properties no relevant deterioration of the thermal insulation properties. Therefore, with the facade insulation board a design value of the thermal conductivity λ <0.040 W / mK can be achieved according to DIN EN 13162, which is very advantageous in terms of energy savings associated therewith.

In addition, it is also achieved by the improved strength properties of the facade insulation board used in the invention compared to the prior art that can be worked with the substantially same number of plate anchors in the attachment of the facade insulation board to an outer wall of a building in the context of a thermal insulation composite system. It thus accounts according to the invention labor-intensive, time-consuming and costly additional work for the attachment of additional plate dowels. In addition, plate anchors with a diameter of the dowel plate of less than 90 mm can be used to attach the facade insulation board.

At the same time, the properties of the facade insulation board on their large surfaces, be it on the outer facade facing surface of the lower layer or the plaster base layer on the outer layer, not affected in the least, so that here from the prior art such as the product "Sillatherm" obtained known excellent properties.

It is indeed from the WO 03/042468 A1 a multi-layer mineral wool fleece for pipe or boiler insulation has become known, in which the binder content can be chosen differently in the individual layers; however, when more than two layers are provided, the binder content here increases from layer to layer across the thickness of the product so that, unlike the article of the present invention, the region having the highest binder level is not present between the outer layers.

Thus, according to the invention, an advantageous composite thermal insulation system can be achieved which, in view of the facade insulation panels used according to the invention, is suitable even for insulation systems with a design value of the thermal conductivity of λ <0.040 W / mK. In particular, however, it is still possible to work with plate anchors, the number of which must not exceed that of conventional facade systems due to the improved mechanical properties of the facade insulation panels. Furthermore, according to the invention it is thus also possible for the first time to design a thermal insulation composite system, for example the heat conduction group 035, with recessed dish dowels.

Moreover, it is thus inventively possible for the first time to perform a thermal insulation composite system in a Wärmeleitgruppe better than WLG 040 with recessed plate dowels with an effective diameter of a dowel plate of less than 90 mm. This also makes the work as well as the cost can be kept very low.

Thus, with the thermal insulation composite system according to the invention can achieve a dowel image on the finished facade, which optically substantially similar to the appearance of a system according to the prior art with plate anchors with a plate diameter of 90 mm and with a λ ≤ 0.036 W / mK is designed while avoiding the thermal bridges of the prior art.

Advantageous developments of the thermal insulation composite system according to the invention are the subject of the dependent claims 2 to 14.

The cover layer may be formed from a mineral wool with a three-dimensional isotropic arrangement of the fibers. Alternatively, the cover layer may consist of compressed mineral wool. In this case, a three-dimensional compression of the mineral wool is preferred, as for example in the DE 198 60 040 A1 which is referred to for technical details. In a third alternative, the cover layer can also be formed as a laminar mineral wool layer with an increased density compared to the laminar lower layer. In this case, the bulk density of this laminar cover layer is more than 150 kg / m ³ , in particular more than 180 kg / m ³ .

It is also possible for the region with a relatively large proportion of binder to essentially contain an outer layer facing the outer layer of the laminar lower layer. It has been found that the added binder in this section allows a particularly effective increase in the strength properties of the facade insulation board. This is due to the orientation of the fibers in a largely parallel manner to the large surfaces of the lower layer. On the one hand, the stiffening of the structure and thus an increase in the transverse tensile strength is achieved here by the increased binder content, and on the other hand, the prevailing orientation of the individual fibers is permitted a particularly good transfer of compressive and tensile forces on adjacent areas in the same plane, so that there is a particularly favorable distribution of forces over a larger area.

It is further advantageous if the mean binder content in the cover layer is greater than the average binder content in the laminar lower layer. It has been shown that this can be improved in a particularly effective manner, the inherent stability of the facade insulation board without this would go to the detriment of the thermal insulation ability to a considerable extent. Within the cover layer, the additional binder brings about a particularly effective connection of the individual fibers and thus an advantageous stiffening of the structure.

Further, it is also possible that the fibers in the cover layer have a larger average diameter than those in the laminar underlayer. It has been shown in experiments that this measure leads to a further stabilization of the outer layer and thus the improvement of the stability of the facade insulation board. In particular, however, the larger diameter fibers in the top layer provide improved distribution of induced forces to adjacent areas, so that transverse tensile loads can be particularly well absorbed by, for example, wind suction forces.

The layer thickness of the cover layer is designed so that after sinking a plate dowel in the cover layer plus possibly deeper outcrops or incisions in the course of dowel insertion remains sufficient for the load transfer residual layer of the cover layer. Due to the comparatively poorer thermal conductivity of the cover layer, it is preferable not to make this layer thicker than necessary. In practical experiments With products of nominal thicknesses of 100 and 120 mm, a ratio of layer thicknesses of about 60% underlayer to 40% top layer has proven to be particularly suitable for achieving a system with a thermal conductivity λ of less than 0.040 W / mK. If the laminar underlayer is thicker than the cover layer, its particularly advantageous properties with regard to thermal insulation can be used effectively for the facade insulation board. As a result of these relationships, the thickness ratio of the outer layer and the lower layer preferably decreases with increasing thicknesses of the facade insulation elements.

If the facade insulation board satisfies a design value of thermal conductivity λ ≦ 0.036 W / mK in accordance with DIN EN 13162, which is possible by the measures according to the invention, it can be used advantageously even for a system of heat conduction group 035 and therefore meets the highest requirements with regard to the regulations for energy saving. The facade insulation board preferably has a design value of the thermal conductivity λ ≦ 0.035 W / mK in accordance with DIN EN 13162.

Furthermore, the effective diameter of the anchor plate may be less than 70 mm, in particular about 60 mm, which can reduce the workload as well as the costs on.

Another advantage is when the facade insulation panels have a recess in the support area of the anchor plate, in which the dowel plate is sunk. Then the dowel plate can sink with proven in practice resources in the facade insulation board, without causing an impairment of adjacent to the sinking fiber structure.

Alternatively, it is also possible that the facade insulation panels have an incision in the support region of the anchor plate whose shape substantially corresponds to the peripheral line of the anchor plate, wherein the anchor plate is recessed in this area in the facade insulation board. Here it has been shown that a removal of the mineral fiber material in the region of the sinking of the plate dowel is not absolutely necessary and the remaining material can even be used to advantage to further improve the strength properties and thus the stability of the system. Although the incision removes the structural relationship between the mineral wool material covered by the dowel plate and the adjacent areas; At the same time, however, the material present here is compressed when tightening the plate dowel and acts as an improved counter bearing for the tightening force of the dowel. The plate dowel sits therefore particularly stable in the facade insulation board and allows an even more reliable fastening the same on the facade. In addition, it has been shown that this compressed mineral wool material under the dowel plate combinatorially cooperates in a particularly advantageous manner with the given in the present invention used facade insulation board layer with increased binder content, so that there is a further improvement in the stability of the system.

The depth of the incision is less than the thickness of the cover layer, wherein the residual thickness of the cover layer remaining at the incision is preferably at least 5%, in particular at least 10%, and particularly preferably at least 20% of the total thickness of the cover layer. About the remaining thickness remaining an advantageous distribution of the loads on adjacent areas within the outer layer is possible. As a result, the stability of the thermal insulation composite system according to the invention can be further improved.

When the recessed dowel plate is covered by a plug, advantageously results in a substantially continuous surface on the outside of the insulating layer. In addition, it is particularly advantageous if the plug consists of mineral wool material, since then there is a uniform material on the outside of the insulating layer throughout. The associated elimination of the thermal bridge then the risk is less, that the points of the plate dowels are visible over the years on the facade.

According to a further aspect of the present invention, the use of a facade insulation board for the insulation of exterior facades of buildings is proposed as part of a thermal insulation composite system according to the invention according to claim 15.

Fig. 1

einen Vertikalschnitt durch ein beispielhaftes Wärmedämm-Verbundsystem gemäß der Erfindung; und

Fig. 2

ein Diagramm, aus welchem beispielhaft eine erfindungsgemäße Bindemittelverteilung innerhalb einer Fassadendämmplatte gezeigt ist.

The invention will be explained in more detail in embodiments with reference to the figures of the drawing. It shows:

Fig. 1

a vertical section through an exemplary composite thermal insulation system according to the invention; and

Fig. 2

a diagram of which an example of a binder distribution according to the invention within a facade insulation board is shown.

As shown in Fig. 1 a thermal insulation composite system 1, which is applied to a facade 2, an adhesive mortar 3, by means of which an insulation layer formed from facade insulation panels 4 is selectively bonded to the facade 2. Furthermore, the thermal insulation composite system 1 on an external plaster 5. How out Fig. 1 it can be seen, the facade insulation panels are 4th also anchored by means of dowels 6 in the facade 2, wherein the plate dowel 6 sunk in the facade insulation board 4 are arranged and the space between the plate dowel 6 and the outer plaster 5 is closed by a plug 7.

In the present embodiments, the thermal insulation composite system 1 is used in the old building renovation. The facade 2 here contains an outer wall 21 and an old plaster 22, which forms a level and stable ground for the thermal insulation composite system 1. In addition, a dowel hole 23 is formed in the facade 2 in a conventional manner, in which the plate dowel 6 is anchored.

The plate anchor 6 includes a dowel plate 61, which has a diameter of 60 mm in the present example. This is integrally formed with a dowel shaft 62, which passes through the facade insulation board 4 and in a conventional manner in cooperation with a dowel screw 63 allows anchoring in the facade 2.

The outer plaster 5 has a flush 51, in which wet in wet a reinforcing fabric 52 is embedded. On the outside, an outer plaster 53 is also arranged.

How out Fig. 1 It can be seen in more detail, the facade insulation board 4 has a lower layer 41 and a cover layer 42, which in the present example are integrally connected to each other by mineral wool nonwoven webs with uncured binder over each other and then cured together in a curing oven. The lower layer 41 in this case has a laminar fiber orientation, ie the The vast majority of the mineral fibers are oriented essentially parallel to the large surfaces of the lower layer 41.

On the other hand, the cover layer 42 has mineral wool in three-dimensional isotropic fiber orientation, i. the fibers contained in this layer are aligned substantially equally in the three spatial dimensions.

How out Fig. 1 It can also be seen that the facade insulation board 4 has an incision 43 which protrudes from the plaster base side of the cover layer 42 by a measure T in the cover layer 42, while leaving a residual thickness of the cover layer 42 of about 15% of the total thickness of this layer unprocessed. The incision 43 can be produced with a so-called can drill, and consequently, in the present exemplary embodiment, the mineral wool material lying within the cut edges is not removed. As in Fig. 1 is indicated, the dowel plate 61 compresses this material within the notch 43 in the course of fastening the facade insulation panel 4 to the facade 2.

Within the facade insulation board 4, the lower layer 41 has an edge layer 41a, which is present in the region of the large surface facing the cover layer 42 on the lower layer 41. The boundary layer between the underlayer 41 and the cover layer 42 is hereby clarified in FIG Fig. 1 schematically indicated by a dashed line.

As in particular from the diagram in Fig. 2 can be seen, this edge layer 41a has a higher binder content than the other areas of the facade insulation board 4. In the present embodiment, the binder content in the topcoat is chosen to be about 5%. The Binder content in the underlayer is in the range of about 3.7% over a wide range, but increased to more than 6% in the surface layer in the example shown. Since this increased amount of binder in the region of the boundary layer, due to process engineering, also penetrates into the edge region of the cover layer 42 in the course of the production of the facade insulation board 4, the result is also close to that in FIG Fig. 2 also indicated by dashed lines boundary layer between the cover layer and the lower layer a slightly increased binder content.

In conjunction with the inherently more sustainable material of the cover layer 42 and in particular the compressed mineral wool material below the dowel plate 61 thus results from this edge layer 41a with increased binder content an insulating layer in the thermal insulation composite system 1, in which a reliable power in the fixation as well as load transfer on adjacent parts for plate dowel 6 is possible. This has an advantageous effect on the stability of the facade insulation panel 4 and the thermal insulation composite system 1.

The facade insulation board 4 can be made in a Zerfaserungsstation like a jet blowing device with, for example, ten consecutively lined blowing nozzles. Of these, in the present exemplary embodiment, six tuyeres can form the mineral wool of the lower layer 41 and four downstream tuyeres form the cover layer 42, wherein in the area of the sixth tuyere for the lower layer 41 a greater amount of binder is added than in the other regions. A primary nonwoven with laminar fiber orientation thus formed is then separated into a first mineral wool raw nonwoven and the second mineral wool raw nonwoven fabric in such a way that the zone with higher binder concentration in an outer layer of the first mineral wool raw nonwoven is present. In a further step, the second mineral wool raw nonwoven is digested and re-combined, resulting in a quasi-isotropic fiber orientation herein. Subsequently, these nonwovens are guided together in such a way that the edge layer is present with a larger proportion of binder in the interior of the combined nonwoven. After curing of the binder, the facade insulation panel 4 can then be made up of it with its outer layer 41 formed by the second mineral wool raw non-woven fabric and the lower layer 41 formed by the first mineral wool non-woven fabric by separating cuts.

In the example shown, the facade insulation board 4 in this case has a total thickness of 100 mm, wherein the cover layer 42 is about 40 mm thick and the lower layer 41 is designed about 60 mm thick. The edge layer 41a is about 10 mm thick in the example shown. By the specified and in Fig. 2 shown binder proportions results for the entire facade insulation board 4, an average binder content of about 4.5%. The bulk density of the cover layer 42 is in the example shown at about 120 kg / m ³ and in the lower layer 41 at about 100 kg / m ³ . The facade insulation board 4 thus reaches a design value of the thermal conductivity λ of about 0.035 W / mK according to DIN EN 13162.

The invention allows in addition to the illustrated embodiment, further design approaches.

For example, the facade insulation panel 4 can also be provided with the following parameters:
The top layer is a three-dimensionally compressed mineral wool according to the procedure of DE 198 60 040 A1 with a bulk density of about 130 kg / m ³ and a binder content of about 4% with a layer thickness provided by about 60 mm. The underlayer with a layer thickness of about 140 mm has a bulk density of about 100 kg / m ³ and a binder content of about 3.5%. The binder content of the boundary layer is adjusted to about 5%, so that there is an average binder content of about 3.9% for the Fassadendämmelement.

In a third embodiment of the invention, the cover layer is provided in the form of a laminar mineral wool layer increased density of about 200 kg / m ³ with a binder content of about 4% with a layer thickness of about 50 mm. The underlayer with a layer thickness of about 110 mm has a bulk density of about 100 kg / m ³ and a binder content of about 3.5%. The binder content of the boundary layer is adjusted to about 5%, so that there is an average binder content of about 3.8% for the Fassadendämmelement.

Alternatively, these two variants can be produced by bonding the hardened layers provided with the parameters mentioned, or the hardened covering layer is fed to a hardening process together with the uncured laminar sublayer.

From a constructional point of view, it is also not necessary for the region with a greater proportion of binder to be present in an outer layer of the lower layer 41. By spraying additional binder on a large surface of the lower layer 41 and / or the cover layer 42 in the course of the manufacturing process, it is also possible, for example, to provide the portion with increased binder content directly at this boundary layer between the two layers, the binder thereby naturally a little in the surfaces of these two layers will enter.

Furthermore, it is not necessary that the mean binder content in the cover layer 42 is greater than the average binder content in the underlayer 41; Rather, these binder proportions can be about the same. It is also possible that the binder content in the entire Fassadendämmplattenquerschnitt with the exception of an edge layer 41a is set at the same level.

The fibers in the cover layer 42 are inventively formed with a larger diameter than those of the lower layer 41; However, this is not absolutely necessary, but also identically configured fibers can be used.

As a material for the facade insulation board 4 rock wool is used in the illustrated embodiment; However, it is also possible to form, for example, the underlayer 41 and / or the cover layer 42 of glass wool.

The ratio of the layer thicknesses of the underlayer 41 to the cover layer 42 is not limited to the factor 60:40 explained and can be varied in both directions, depending on the application.

Claims (15)

1. A composite thermal insulation system (1) for the insulation of external facades (2) of buildings, comprising:

   an insulating layer of facade insulation boards (4), which are formed of bound mineral wool and comprise a bottom layer (41) and a top layer (42), wherein the top layer (42) includes mineral wool having an elevated mechanical strength in comparison with the bottom layer, and

   an external rendering (5),

   wherein the facade insulation boards (4) are adapted to be bonded to the building facade (2) and adapted to be fixed by means of washer dowels (6) and serve as mortar carrier boards for the external rendering (5),

   wherein the washer dowels (6) are disposed underneath the external rendering (5), and

   wherein the washer dowels (6) are disposed sunk in the top layer (42) of the facade insulation boards (4) and have an effective dowel washer diameter (61) of less than 90 mm,

   characterized in that

   the facade insulation boards (4) satisfy a rated thermal conductivity value λ < 0.040 W/mK according to DIN EN 13162,

   the bottom layer (41) is formed of laminar mineral wool, and

   the binder content in the area of a boundary layer between the top layer (42) and the laminar bottom layer (41) is higher than in the other areas of the facade insulation board (4).
2. The composite thermal insulation system according to claim 1, characterized in that the top layer includes mineral wool in three-dimensionally isotropic orientation.
3. The composite thermal insulation system according to claim 1, characterized in that the top layer is formed of upset mineral wool, in particular of three-dimensionally upset mineral wool.
4. The composite thermal insulation system according to claim 1, characterized in that the top layer consists of laminar mineral wool having an elevated bulk density, preferably more than 150 kg/m³, and in particular more than 180 kg/m³.
5. The composite thermal insulation system according to any one of claims 1 to 4, characterized in that the area having a higher binder content essentially contains a marginal layer (41a) of the laminar bottom layer (41) which faces the top layer (42).
6. The composite thermal insulation system according to any one of claims 1 to 5, characterized in that the mean binder content in the top layer (42) is higher than the mean binder content in the laminar bottom layer (41).
7. The composite thermal insulation system according to any one of claims 1 to 6, characterized in that the fibers in the top layer (42) have a greater mean diameter than those in the laminar bottom layer (41).
8. The composite thermal insulation system according to any one of claims 1 to 7, characterized in that the laminar bottom layer (41) is formed at a greater thickness than the top layer (42).
9. The composite thermal insulation system according to any one of claims 1 to 8, characterized in that it satisfies a rated thermal conductivity value λ ≤ 0.036 W/mK, preferably λ ≤ 0.035 W/mK, according to DIN EN 13162.
10. The composite thermal insulation system according to any one of claims 1 to 9, characterized in that the effective diameter of the dowel washer (61) is less than 70 mm, in particular approx. 60 mm.
11. The composite thermal insulation system according to any one of claims 1 to 10, characterized in that the facade insulation boards (4) include a recess for sinking the dowel washer (61) in the contact area of the dowel washers (61).
12. The composite thermal insulation system according to any one of claims 1 to 10, characterized in that the facade insulation boards (4) have in the contact area of the dowel washers (61) an incision (43) having a configuration that substantially corresponds to the peripheral contour of the dowel washers (61), wherein the dowel washer (61) is sunk in the facade insulation board (4) in this area.
13. The composite thermal insulation system according to claim 12, characterized in that a depth (T) of the incision (43) is less than the thickness of the top layer (42), with the residual thickness of the top layer (42) remaining at the incision (43) being preferably at least 5%, in particular at least 10%, and in a particularly preferred manner at least 20% of the total thickness of the top layer (42).
14. The composite thermal insulation system according to any one of claims 11 to 13, characterized in that the sunk dowel washer (61) is covered by a plug (7), in particular one of mineral wool material.
15. Use of a facade insulation board (4) for the insulation of external facades (2) of buildings as a constituent of a composite thermal insulation system (1) according to any one of claims 1 to 14,
    wherein the facade insulation board (4) is formed of bound mineral wool and satisfies a rated thermal conductivity value λ < 0.040 W/mK according to DIN EN 13162,
    wherein it comprises a bottom layer (41) and a top layer (42),
    wherein the bottom layer (41) is formed of laminar mineral wool,
    wherein the top layer (42) includes mineral wool having an elevated mechanical strength in comparison with the bottom layer, and
    wherein the binder content in the area of a boundary layer between the top layer (42) and the laminar bottom layer (41) is higher than in the other areas of the facade insulation board (4).

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